Patent GB-312476-A (GB)
Title: Improvement in apparatus for simultaneously machining the opposite faces of an article
IPC: B23B9/10
Filed: 1928-05-10
Abstract: 312,476. Jacobowitz, A., and Mars-Werke Akt.-Ges. May 10, 1928 Drilling-machines ; drills and cutters.-In a machine for simultaneously operating on opposite sides of a workpiece by means of four rotary cutter spindles arranged in axially opposed pairs and fed axially by cams, one pair of opposed spindles is adjustable laterally in relation to the other pair so as to be capable of operating on work pieces of different lengths, the driving gearing for the adjustable spindles being so arranged that the drive is not interrupted when small adjustments are made. As applied to a machine for operating on cranks of bicycles a bed 24, Figs. 1 and 2, supports a work-holder 55 and carries four headstocks 1- - 4, the headstock 1 being stationarilv secured to the bed, the headstock 2 being slidable on the bed parallel to its tool-spindle 26 and the headstocks 3 and 4 being transversely movable on guides 5, 6, which are axially adjustable on the bed. The headstocks 1 - - 3 carry tools 7<1>, 26' and 41', for boring and facing the ends of a cycle crank 25 as shown in Fig. 10, while the headstock 4 carries a screw tap 49'. The spindle 7 of the headstock 1 is led axially by a cam 21, Figs. 2 and 7, acting on a roller carried by a slide 19 attached to a rear extension of the spindle. The headstocks 2- - 4 are fed by cams 30, 43, 54 respectively, acting on rollers carried by brackets 29, 42 on the headstocks. The spindles 7, 26 are driven by gearing 15, 28, Fig. 2, from a spindle shaft 23 rotated through bevel gearing 34 from a main drive shaft 33 driven from a belt pulley 31 through a clutch 32 controlled by a hand operated lever. The main shaft 33 also drives the remaining tool-spindles and the cam shafts. The spindle 41 is driven by gearing 69 from a shaft 36 connected by splined bevel gears 35 to the shaft 33 and the spindle 49 is driven by gearing 48 from a sleeve 46 which is rotated through reversing gearing 50 from a shaft 45 connected by gearing 40 to a shaft 39 geared at 37 to the shaft 36. The shaft 39 is journaled in the slides 5, 6, and the shaft 36, 45 in the headstocks 3, 4, so that a small lateral adjustment of these headstocks is possible without interrupting the drive of their spindles. The four feeding cams are mounted on shafts' 22, 44, each of which carries a central worm-wheel engaged by a pair of worms on a transverse shaft 56 which is rotated through a clutch 58, a chain drive 68 and gearing 67 from the main shaft 33. When it is desired to drill a hole in the work perpendicular to the axis of the spindles 7, 26, a vertical bracket 79, Fig. 11, is attached to the work-holder 55 and is provided with vertical guides supporting a drill-head 78. A drill-spindle 77 carried by the head is driven through splined gearing 76, 74, vertical shaft 73, and bevel gearing 71 from the shaft 23 which drives the spindles 7, 26. A spring 82 normally holds the head in its raised position and the downward feed is produced by a cam 80 acting on a roller 81 attached to the head. The cam is mounted on a shaft 84 connected by a clutch 86, hand operated at 87, to a worm-wheel engaging a worm on a vertical shaft 92 which is driven by bevel gearing 91 and spur gearing 89 from the shaft 56 which rotates the cam shafts 22, 44. A lever 94 provides for hand feed of the drill when the cam clutch 86 is thrown out. Milling-machines ; milling-cutters.-The drillspindle 7, Figs. 2 and 7 is rotatably mounted on a sleeve 9 which also has rotatably mounted therein a spindle 13 carrying a milling cutter 13<1>, the spindle 13 being rotated by gearing 14 from the spindle 7. The sleeve 9 is rotated in the. headstock 1 by gearing 10 from the cam shaft 22 so as to give the cutter 13<1> a planetary motion to machine the outside of the hub on the cycle crank as shown in Fig. 10. Tapping-machines.-A clutch 51, Fig. 2, is splined to the shaft 46 and is movable by adjust. able stops 52 on the slide 6, coacting with a fixed stop 53, to connect either of the two bevel wheels 50, 50<1> to the shaft. The bevel wheel 50 carries a gear engaging a gear 48 splined to the tapspindle 49 to rotate the tap 49<1> in either direction, springs 48<1> serving to give the spindle a yielding feed when the slide 6 is traversed by the cam 54. Operation.-In operation, the crank 25 is secured in the holder 55 and brought into position when the machine is idle. The clutch 32 is then engaged, causing all the tool-spindles to be rotated, whereupon a spindle on the holder 55 is actuated to cause the work to be brought into contact with the rotating milling cutter 13<1>, a ratchet or catch (not shown) being provided for indicating when the the crank eyes are exactly opposite the appropriate, tool-spindles. The clutch 58 is then engaged and the tools are fed axially into the work while the milling cutter executes a planetary motion round the hub of the crank. The drilling tool 41<1> operates more quickly than the other cutters so that the tap 49' may act after it has been withdrawn. If the vertical drill-head 78 is used, the drill comes into operation before or after the tools 7<1>, 26<1> have acted. When the headstocks have returned to their retracted positions the main clutch 32 is automatically disengaged and when the work is removed from the holder the cam-shaft clutch 58 is automatically thrown out to prevent the cams from coming into operation when the main clutch is re-engaged. If desired, the milling cutter 13<1> may be omitted.